Important bug fix: condition to check for do_matrix_multiply was sometimes failing due to integer overflow.
Fixed new hams/Heisenberg to include 2d square lattice case.
Removed unecessary assignToVec call from MPSt::checkOrtho
Removed unused tensor assignFromVec methods.
Added some convenience methods to Global:: for adding and getting Opts. Simplified OptSet by removing unused and confusing methods for getting Opts by passing an instance.
Fixed unit test to compile with latest changes to option.h.
Changed ApproxReal_Accuracy back to 1E-12.